In this work, the effectiveness of phenolic compounds of different varieties of wines as antibacterial agent in a meat model system was determined. Total phenolic, flavonoid and flavanol compounds concentrations were greater inMerlot andMalbec wines compared with Cabernet Sauvignon variety. In meat, the best antibacterial effect of wine phenolic compounds against both bacteria was observed withMerlot and Malbec wine varieties at 4C, even when inhibitory effect was also observed at 20C. The lowest decimal reduction time was obtained withMerlot wine for Listeriamonocytogenes and with Malbec and Merlot wines for Escherichia coli. From our results,we propose the use of wine phenolic compounds as natural biopreservatives for meat in combination with low temperatures. These natural products provide the additional human health benefit inherent to polyphenols properties. The exploration of natural antimicrobials for food preservation receives increased attention due to a growing microbial resistance towards conventional preservatives, added to consumer awareness of natural food products. The antibacterial effect of individual phenolic compounds in culturemedia has been largely studied,, but there is no information about the antibacterial effect of natural combinations of polyphenols fromdifferent varieties of wines in meat. In thiswork,we demonstrate that phenolic compounds combination of Argentinean wines were effective in inhibiting the growth of two pathogenic bacteria that produce food contamination and illness in the consumer.Natural polyphenol combinations found in Argentinean wines could act as natural biopreservatives for meat in combination with low temperatures, achieving extension of the shelf life of food.

The aim of the present study was to evaluate the inhibitory effect by the cross-streak method of nine Enterococcus faecium strains isolated from faeces of healthy dogs and their treated and non-treated cell-free supernatant (CFS) by the well-diffusion test on the growth of potentially pathogenic bacteria isolated from clinical cases and aflatoxigenic Aspergillus section Flavi and the consequent aflatoxin B1 (AFB1) production. Results obtained from the cross-strake assay showed that E. faecium MF1, GJ18 and GJ40 presented the major inhibitory activity against all pathogenic strains assayed; E. faecium GJ40 produced the larger inhibitory zones (26–27 mm). Well-diffusion test results showed that the majority of the enterococci strains CFS had antimicrobial activity against the pathogenic microorganisms, especially on Gram negative indicators. Cell-free supernatant of E. faecium GJ40 was the one that produced the largest inhibition zones (14 to 21 mm) in the majority of the indicator microorganisms assayed. All supernatants treated with 10 N NaOH (pH6) showed no inhibitory effect on the indicator strain assayed. With respect to fungal inhibition, any of the CFS assayed significantly inhibited the Aspergillus strains growth. But, in general, all CFS reduced AFB1 production from 8 to 87%. The results demonstrate that enterococci isolated from healthy dog feaces produce substances with the capacity to inhibit some potential pathogenic bacteria growth and the capacity of inhibiting or reducing the AFB1 production in vitro.

The objective of this study was to determine the prevalence of major mastitis pathogens in bulk tank milk from dairy herds located in the central dairy area of Argentina. In addition, performance of three culture media, two standard (Baird Parker and blood agar) and one commercial (Dry Compact “Nissui”) for Staphylococcus aureus detection and enumeration was evaluated. Prevalence of S. aureus, Streptococcus agalactiae, Streptococcus uberis and Streptococcus dysgalactiae was 50%, 5.45%, 31.82 and 12.72, respectively, while Mycoplasma spp. was not detected. Regarding culture media performance, accordance between Baird Parker and blood agar was moderate to low, although higher than the one observed between Baird Parker and Compact Dry “Nissui”. Colony recovery percent on blood agar or Compact Dry “Nissui” did not differ from Baird Parker, being higher on Compact Dry “Nissui” and lower on blood agar. These results stress the need to control major mastitis contagious pathogens in the central dairy area. All culture media evaluated were found suitable for detection and enumeration of S. aureus in bulk tank milk

We previously showed that the opportunistic nosocomial pathogen Acinetobacter baumannii is able to sense and respond to light via BlsA, a BLUF (Blue-Light-sensing Using FAD)-domain photoreceptor protein. Here, we extend our previous studies showing that light regulation is not restricted to A. baumannii, but rather widespread within the genus Acinetobacter. First, we found that blue light modulates motility and biofilm formation in many species of the genus, including members of the Acinetobacter calcoaceticus-A. baumannii complex. In many of these species blue light acts as a key factor guiding the decision between motility or sessility at 24uC, whereas in A. baumannii, light inhibits both motility and biofilm formation. We also show that light regulation of motility occurred not only at 24uC but also at 37uC in non-A. baumannii species, contrasting the situation of A. baumannii which only shows photoregulation at 24uC. Second, we show that Acinetobacter baylyi (strain ADP1) BLUF-photoreceptors can functionally replace in vivo the A. baumannii 17978 BlsA protein and that the pathways leading to biofilm formation are inversely regulated at 24uC between these two microorganisms. Finally, we found the presence of predicted genes coding BLUF-containing proteins in all Acinetobacter sequenced genomes, even though the copy number is variable among them. Phylogenetic analysis suggests a common origin for all BLUF domains present in members of this genus, and could distinguish well-differentiated clusters that group together BLUF homologs from different species, a situation particularly clear for members of the ACB complex. Despite a role played by these BLUF domain-containing proteins in the photoregulation observed in the members of the genus Acinetobacter is a likely scenario given our findings in A. baumannii and A. baylyi, further research will contribute to confirm this possibility.